Integrating xclingo to an existing clingo pipeline

[zl-xiang]

Hi @bramucas ,

I understand the pipeline of current version of xclingo (2.0b14) does the following (correct me if I'm wrong):

1. taking a base program (BP) as input
2. translating BP and combining it with the program defined in xclingo.lp as the explaination program (EP)
3. grounding&sovling BP with a clingo control instance defined in XclingoControl
4. taking ground atoms from the derived models from step 3, wrapping them with _xclingo_model predicate
5. grounding the EP in step 2 with the ground facts generated from step 4 and solving the grounded EP with a new clingo control instance to get the explaination

Therefore, I integrated the existing clingo applicaltion of my by replacing the clingo control instance in step 3 with my own one, which has a customised context object inherited the Context class defined in _main.py.

In this case, BP derives stable models normally but I always get UNSAT by solving EP. It's quite strange since EP doesn't have any integrity constraint.

Do you have an idea what might be the issue here?

P.S. my EP looks like this, only rule 7 and 12 are annotated with %!trace_rule:
xclingo-trans22.txt

Thanks a lot,
Zhiliang